flush to get out any nutes. if you had bugs at all in your last grow then either don;t use the soil or sterilize it by baking it. check it for drainage and add more perlite if needed.
Leaching the soil is in order. (a massive flush) Then dry out 100%. Sift out the old roots and crap. add some amendments and use it at 1/3 to 2/3 new soil. Let the rest just sit and bake.
Repeat as necessary.
dirt cheap lol. dirt is kinda expensive haha. but yeah i pretty much determined that it's not worth it to re-use dirt. with baking it using gas. filtering it. and all the other stuff you need to do. thanks drama for your reply.